At present, electronic and electrical components such as central processing units (CPUs) are continuing to be developed to have faster operational speeds and greater functional capabilities. A CPU may be mounted in a limited space within a computer enclosure, and when the CPU operates at high speeds, its temperature may increase greatly. Thus, it is desirable to quickly dissipate the heat generated by the CPU. Similarly, many devices such as internal combustion engines of motor vehicles ordinarily generate much heat, and may generate vast amounts of heat when operating at high capacity. It is desirable to quickly dissipate the heat generated by an engine.
Numerous kinds of heat dissipation systems have been developed for cooling electronic, electrical and mechanical components. For example, heat pipes are commonly used in computer enclosures. A typical heat pipe includes an evaporation section for absorbing heat and a condensation section for dissipating heat. Working fluid is contained in a wick formed on an inner wall of the heat pipe. The working fluid transfers heat from the evaporation section to the condensation section by way of phase change.
In general, the heat pipe is vacuumized at a desired vacuum pressure, e.g., generally between 1.3×10−1 and 1.3×10−4 Pa (pascal). This helps speed the flow of the working fluid. When the heat pipe is manufactured and vacuumized, the vacuumizing is generally performed after the working fluid is filled into the heat pipe. However, the working fluid is generally comprised of a volatile fluid, for example, methanol, alcohol, acetone, ammonia, heptane, etc. Thus during the vacuumizing process, a certain small amount of working fluid is usually sucked out of the heat pipe together with air. This results in the actual filling volume of the working fluid being less than the preset desired filling volume. The short fall of the actual filling volume may be significant, as detailed below.
The preset filling volume of the working fluid is generally calculated so that the working fluid is accommodated in the wick to an extent whereby the capillary capability of the wick is optimal. If the actual filling volume is less than the preset filling volume, a part of the wick (generally in the evaporation section) is prone to be prematurely dried out. On the contrary, if the actual filling volume is more than the preset filling volume, the wick may be overburdened with working fluid whereby the capillary capability of the wick is limited. In both of these error situations, the thermal efficiency of the heat pipe is decreased.
To attain the exact preset filling volume, one approach used is to simultaneously perform the vacuumizing process and the working fluid filling process. However, this approach requires that the two processes be carefully operated and monitored, and in general a large sophisticated apparatus is required. Even then, it can still be difficult to accurately control the filling volume of the working fluid into the heat pipe.
What is needed, therefore, is a fluid filling system for a vacuum container, wherein the fluid filling system is relatively compact and is able to accurately control the filling of working fluid into a heat pipe to reach a predetermined filling volume.
What is also needed is a fluid filling method for a vacuum container using a fluid filling system having the above-described advantages.